Year	% of total energy
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	2.0804220841950447
1991	2.324487551880038
1992	3.5369798829679016
1993	3.4528575967278075
1994	3.3351649926403817
1995	2.7983894532535913
1996	2.7446243231477507
1997	2.9335954556417203
1998	3.1299257245582663
1999	3.4737355705077877
2000	3.114752944097972
2001	3.258470174566124
2002	3.6365985597094626
2003	3.459378920646404
2004	3.5483019343089506
2005	3.730536860114276
2006	3.8215089511969884
2007	4.0085158227082145
2008	4.419850524090909
2009	5.173714498793423
2010	5.151406687279964
2011	5.60913532968093
2012	5.810263100559246
2013	6.205196854823225
2014	6.601765764544974
2015	6.819180379081473